This invention relates generally to electrical connectors, and more particularly, to power utility connectors for mechanically and electrically connecting a tap or distribution conductor to a main electrical transmission conductor.
Electrical utility firms constructing, operating and maintaining overhead and/or underground power distribution networks and systems utilize connectors to tap main power transmission conductors and feed electrical power to distribution line conductors, sometimes referred to as tap conductors. The main power line conductors and the tap conductors are typically high voltage cables that are relatively large in diameter, and the main power line conductor may be differently sized from the tap conductor, requiring specially designed connector components to adequately connect tap conductors to main power line conductors. Generally speaking, three types of connectors are commonly used for such purposes, namely bolt-on connectors, compression-type connectors, and wedge connectors.
Bolt-on connectors typically employ die-cast metal connector pieces or connector halves formed as mirror images of one another, sometimes referred to as clam shell connectors. Each of the connector halves defines opposing channels that axially receive the main power conductor and the tap conductor, respectively, and the connector halves are bolted to one another to clamp the metal connector pieces to the conductors. Such bolt-on connectors have been widely accepted in the industry primarily due to their ease of installation, but such connectors are not without disadvantages. Hand tools, such as a torque wrench, are often utilized to tighten the bolt to clamp the connector pieces together. Because a high torque is required to tighten the bolt, the quality of the connection is dependent upon the relative strength and skill of the installer, and widely varying quality of connections may result. Additionally, the quality of the connection depends upon the amount of metal-to-metal engagement between the connector pieces and the conductors. When the engagement surfaces of the connector pieces and/or the conductors are oxidized, dirty or otherwise contaminated, a poor connection results. Poorly installed or improperly installed compression connectors can present reliability issues in power distribution systems.
Compression connectors, instead of utilizing separate connector pieces, may include a single metal piece connector that is bent or deformed around the main power conductor and the tap conductor to clamp them to one another. Such compression connectors are generally available at a lower cost than bolt-on connectors, but are more difficult to install. Hand tools are often utilized to bend the connector around the cables, and because the quality of the connection is dependent upon the relative strength and skill of the installer, widely varying quality of connections may result. Poorly installed or improperly installed compression connectors can present reliability issues in power distribution systems.
Wedge connectors are also known that include a C-shaped channel member that hooks over the main power conductor and the tap conductor, and a wedge member having channels in its opposing sides is driven through the C-shaped member, deflecting the ends of the C-shaped member and clamping the conductors between the channels in the wedge member and the ends of the C-shaped member. One such wedge connector is commercially available from Tyco Electronics Corporation of Harrisburg, Pa. and is known as an AMPACT Tap or Stirrup Connector. AMPACT connectors, however, tend to be more expensive than either bolt-on or compression connectors. Additionally, because of the high force needed to drive the wedge member into the C-shaped member, special application tooling using explosive cartridges packed with gunpowder has been developed to drive the wedge member into the C-shaped member. Such tooling is expensive and potentially dangerous to operate. Different connectors and tools are available for various sizes of conductors in the field.
AMPACT connectors are believed to provide superior performance over bolt-on and compression connectors. For example, the AMPACT connector results in a wiping contact surface that provides good electrical contact between the connectors and the conductors. Unlike conventional bolt-on and compression connectors, the AMPACT connector is stable, repeatable, and consistently applied to the conductors, and the quality of the mechanical and electrical connection is not as dependent on torque requirements and/or relative skill of the installer. Additionally, and unlike bolt-on or compression connectors, because of the deflection of the ends of the C-shaped member some elastic range is present wherein the ends of the C-shaped member may spring back and compensate for relative compressible deformation or movement of the conductors with respect to the wedge and/or the C-shaped member.
It would be desirable to provide a lower cost, more universally applicable alternative to conventional power utility connectors.